[llvm-branch-commits] [NFC][Matrix] Make CreateLoop take ConstantInt for Bound/Step (PR #181291)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/181291

These should always be constants (unless someday we add support for
scalable matrices and then we can revisit). Explicitly pass them as
ConstantInt so we can avoid needing to downcast in a future PR that will
calculate appropriate branch weights using these values.